It is well known to communicate signals via optical fibers, to which end it is known to convert a signal between electrical and optical forms using an electro-optic device, such as a light-emitting diode for an optical transmitter or a photodiode for a light receiver. In order to couple light effectively between the electro-optic device and an optical fiber, it is known to use a lens such as a graded index (GRIN) lens as a focusing element between the device and the end of the fiber.
Especially in the field of telecommunications, increasing capacity and density of electronic components have resulted in an increasing need for many optical fibers to be coupled to a single electronic circuit card. For example, in the case of optical line interface circuits for telecommunications switching equipment, several interface circuits, comprising optical transmitters and receivers, may be accommodated on a single card. In order to communicate the optical signals, a respective optical fiber must be accurately coupled to and aligned with each optical device. In addition to the difficulty of accommodating the required number of optical fiber connectors within the available physical space, the necessary alignment of the fibers to the devices is a labour-intensive and consequently expensive task.
Although each such fiber may carry signals at only a relatively low bit rate, for example of the order of 50 Mb/s, multiplexing of signals on the fibers, thereby to reduce the number of fibers and corresponding connectors needed, is not practical because the fibers may be coupled at their far ends to equipment which operates at this relatively low bit rate, or different fibers may extend to different locations.
Accordingly, a need exists to facilitate the coupling of fibers to electro-optic devices in a manner which provides a compact arrangement and facilitates alignment. An object of this invention is to provide a multi-path electro-optic transducer which satisfies this need.